Sliding gear lock



OR 2.440.175 SR SearchRoom y 1948- H. A. LAND 2,440,775

SLIDING GEAR LOCK Filed D90. 26, 1944 fivezziar: jyarry caijarzd.

Search Room Patented M8? 4,

UNITED STATES PATENT OFFICE SLIDING GEAR LOCK Harry A. Land, Chicago, Ill., assignor to International Harvester Company, a corporation of New Jersey Application December 26, 1944, Serial No. 569,677

1 Claim. (01. 287-52.05)

This invention relates to a power-transmitting melghanism. More specifically it relates to a gear 100 In the use of shifting gears for engagement and disengagement such as are widely used in transmissions for automotive vehicles difliculties are often encountered in maintaining the gears in wardly projecting housing l2 which provides a support for pivotally mounting a gear shift lever I3. Said gear shift lever extends within the transmission housing i and has a headed end portion l4 adapted to engage a notch I5 in a shifter rod it. As is conventional in transmissions of this type, a plurality of shifter rods 16 are usually engagement. Various theories have been adprovided, the gear shift lever 13 being engageable vanced as to why the gears tend to creep out of with notches similar to the notch i5 formed inthe engagement as theoretically there is no force actshifter rods. ing in an axial direction which would tend to The shifter rod I6 is provided with a downforce the gears out of engagement. There is alwardly extending shifter fork l1 whichis bifurways a certain amount of eccentricity and out-ofcated'at its lower end to eng e a collar i8 formed roundness regardless of the accuracy of the main the extending hub IQ of a toothed gear 20. chine operations. Apparently an action develops Said gear is splined internally, the keys or splines similar to that employed in the common expedibeing designated by the reference character 2| ents of removing a tightly fitting cork from a and the spaces between the splines being desigbottle. Any slight wobbling action of a gear nated by the reference character 22. Said splines splined on a shaft for axial sliding movement with fit between splines 23 formed on a, power transrespect thereto may have the result of developing mltting shaft 24, wh r saidmis mounted a force tending to move the slidable gear in an for axial sliding movement on the shaft 24. axial direction. The force sometimes becomes so The gear 2li is adapted to mesh as illustrated great that anchoring the shifter fork is not a with a gear 25 which is one of several of a gear practical solution due to the friction developed by cluster 26, said gear cluster including a plurality engagement of the shifter fork with the gear. 25 of additional gears which form a part of the The present invention contemplates a simple power-transmitting mechanism. effective means of looking a gear against acci- In Figure 1, the gear 20 is shown in neutral or dental displacement when a load is being applied non-driving position. It will be understood that thereto while permitting movement of the gear the gear is shiftable by the gear shift lever II to when very little load is being applied thereto. the right into meshing engagement with the gear In principle the invention contemplates the use 25. It will be noted that the righthand portions of a gear which closely fits in a radial direction of the splines 23 on the shaft 24. as shown in Figon a spline shaft to maintain the gear in conure 1, are indicated as being substantially thinner centric driving relation while and at the same than the main portion of the teeth. This thinner time undercutting the splines in a circumferential portion will be identified by the reference chardircction to provide abutting shoulders which acter 23'. The reduced portion 23' extends to the positively hold the gear against axial movement right a suiiicient distance so that the extension when a substantial torque is being applied hub .l9 on the gear 20 slides over those portions thereto. 23' of the splines or-keys 23 having normal cross- In th drawing section and past shoulders 21 formed at the June- Flgure 1 shows a section of an automotive vetion of the portions 29 and the reduced portions hicle transmission with a portion broken away in 23'. For the purpose of illustration, the differsection to illustrate a sliding gear arrangement ence in circumferential widths between the spline within the transmission; portions 22* and 23 has been greatly exaggerated. Figure 2 is an enlarged sectional detail taken In actual practice this difference amolmts to only on the line 2-2 of Figure 1 showing the undercut a few thousandths of an inch. The shoulder 2! portion of the splines; and would probably, therefore, not be visible to the Figure 3 is an enlarged detail showing the spline eye except by reflected light and be hardly more shaft with one of the splines in plan view and the than perceptible to touch. Figures 2 and 3 have adjacent portion or the gear hub in section. been exaggerated in proportion relatively more A transmission housing I I as shown in Figure than Figure 1 to show the shoulders 21. and the 1 may be, for example, a portion of a tractor manner in which they operate to prevent the gear which-is driven by an internal combustion engine from creeping out of driving position. As the and in which a change-speed gear mechanism is spaces 22 between the keys or splines 2| on the gear 2| are of the width of the spline portions 22' incorporated. A cover housing I I includes an upon the shaft, said spaces are substantially greater in circumferential width than the spline portions 23 After the gear has been moved into engaging position with the gear and driving torque is applied to said gears, the gear 20 assumes the position shown in Figures 2 and 3. If driving torque is in an opposite angular direction. the same general principle will move the other side of the keys 2| into engagement with the spline portions 23, whereby a lock will be effected by the shoulders 21 at the other side of the splines. It will be understood that with driving torque applied to the gears, the gear 20 will be held against axial movement by engagement with the shoulders 21 even though these shoulders are'only 1 a few thousandths of an inch in circumferential measurement. It will also be evident that when driving torque is not being applied to the gears, the back lash between the gear teeth and the tolerance necessary for sliding fits will permit the an operator to slide the gear 20 over the shoulders 21 onto the spline portions 23 In the construction of splines as used to a reat extent in modern practice, concentricity is ob- .4 position on the shaft 24 and to hold it on an axis parallel with the axis of the shaft 24. This particular fitting either at the circumferential faces of the splines 23 or at the circumferential faces of the splines 2| is an essential and significant feature of the present construction.

Applicant claims as his construction all modifications of gear locking mechanism falling withing the scope of the appended claim.

I 'l I circumferentially of the shaft at one portion thereof than at an axially adjacent portion to tained by the centering action of the splines on a 25 shaft with respect to the splines on the gear. It is obvious that with the large amount of clearance provided in a circumferential direction in the present construction, concentricity cannot be obtained by fitting action of the splines on their radially extending faces. It is, therefore, necessary in this construction to provide a very close sliding fit between circumferential faces at the tips of the splines on one member and root faces 5 provide shoulders on said splines coincident with o s d p es, a gear havin g agssla fm atem mesheew shaftsplines and slidable axially Bfthe shaft selectively from either of such portions to the other while maintaining the meshed relation of said splines, there being root faces on the gear between its splines and circumferential faces on the radially inner sides of such splines, said gear being slidably carried on the shaft exclusively by the engagement of the root faces of at least one of said spline sets with the circumferential faces of the other set, to maintain a coaxial relation between the gear and shaft irrespective of the shaft portion occupied by the gear and to facilitate limited relative rotation of the gear and shaft to axially align end portions of the gear splines with said shoulders while the on the other member between its splines. Such 8 0001119185 the axially adjacent Shaft P o circumferential faces on the splines are indicated at 2| and 2-4 respectively on the gear and shaft while the root faces are indicated at 28 and 28*. This close sliding fit might be used for both sets of circumferential faces and the root faces opposed thereto radially of the shaft. However, such construction would require very accurate fitting, and it is only necessary to fit one set of the circumferential faces with their opposed root faces on the other member. As illustrated, the root faces 28 are closely fitted on the circumferential faces 24 between the splines 23. This fitting is such'as to hold the gear in concentric HARRY A. LAND.

REFERENCES CITED The following references are of record in the 40 file of this patent:

UNITED STATES PATENTS 

